Field of the Invention
The invention relates to an adaptive contrast enhancement apparatus and method, and more particularly, to an adaptive contrast enhancement apparatus and method that adaptively assign steep mapping functions to darker images and moderate mapping functions to brighter images so that all kinds of images may be properly adjusted to enhance contrast.
Description of the Related Art
In conventional contrast enhancement methods, an input image signal is mapped to an output image signal according to a mapping function (e.g., a gamma correction curve) that adjusts the relative brightness of low-brightness regions and high-brightness regions so that the contrast of the image may be adjusted. However, it is impossible for conventional gamma correction curves with simple and fixed function values to properly enhance contrasts of various images which may have strikingly different distributions of low-brightness and high-brightness pixels; therefore, an improved contrast enhancement method adaptive to all kinds of images with different brightness distributions is required.